1. Field of the Invention
The present invention concerns methods and apparatus for cleaning channels or passageways, and for cleaning the working channel of an endoscope in particular.
2. Related Art
Endoscopes are medical instruments which permit minimally invasive medical examinations of, and surgery on, internal body tissues (e.g., angioscopy, arthroscopy, choledochoscopy, colonascopy, colposcopy, sinus surgery, gastroscopy, hysteroscopy, tracheal intubation, laparoscopic surgery, plastic surgery, thoracoscopy, urology, etc.). Basically, an endoscope includes an insertion tube having a distal end and a proximal end, and a scope body coupled with the proximal end of the insertion tube and having means for rendering an image captured at the distal end of the insertion tube. In medical applications, the insertion tube is inserted through a small incision or a body orifice. The insertion tube then relays an image, received at its distal end, where the image is captured within a patient's body, to its proximal end, where the image is rendered outside of the patient's body.
Although one skilled in the art understands the features and operation of flexible endoscopes, a brief description is provided below for the reader's convenience.
FIG. 8a is a side view of a flexible fiberscope 800. The flexible fiberscope 800 includes a control section 802 and an insertion tube 804. The insertion tube 804 is flexible such that its distal end may be articulated left and right, by means of left-right articulation control 810, and up and down, by means of up-down articulation control 814. The left-right articulation control 810 may be locked by brake 812, and the up-down articulation control 814 may be locked by brake 816. The control section 802 also includes a diopter adjusting ring 806 and an eyepiece 808. An adapter (not shown) may be used to connect a video camera (not shown) to the eyepiece 808. Finally, a light guide connector 818 permits connection to an external light source (not shown), as well as sources of air (or other gases) and water.
FIG. 8b is a cross-sectional side view, and FIG. 8c is an end view, of the distal end of the insertion tube 804 of the flexible fiberscope 800 of FIG. 8a. Wall 822 defines an outer cylinder and wall 840 defines an inner cylinder. Within the space 824 defined by the inner cylinder, a bundle of coherent optical fibers 830 carries an image focused on a distal end of the fiber bundle 830 by an objective lens 832. A fiberoptic or liquid light guide 826, which serve as illumination means, and working channel(s) 828, which can accommodate sensors and/or tools, are located between the inner and outer cylinders.
FIG. 9a is a side view of a flexible video endoscope 900. As with the flexible fiberscope 800 discussed above, the flexible video endoscope 900 also includes a control section 902 and a flexible insertion tube 904. The distal end of the flexible insertion tube 904 may be articulated left and right, by means of left-right articulation control 908, and up and down, by means of up-down articulation control 912. The left-right articulation control 908 may be locked by brake 910, and the up-down articulation control 912 may be locked by brake 914. Finally, a light guide and video cable 918 permits connection to an external light source (not shown), as well as sources of air (or other gases) and water via connector 920, and to a camera control unit (not shown), via connector 922.
Unlike the flexible fiberscope 800 discussed above, the video endoscope 900 does not have focus or diopter adjustment rings, nor does it have an eyepiece. This is because, as alluded to above, the video endoscope 900 provides a video output to an external camera control unit. More specifically, as shown in FIG. 9b, which is a partial cut-away, perspective view of the distal end of the insertion tube 904 of the video endoscope 900 of FIG. 9a, an objective lens 950 focuses an image 958' of an object 958 in its field of view 956, onto an imaging device, such as a charge coupled device (or "CCD") 952 for example. The CCD 952 (and associated circuitry) provides a sequence of analog waveforms based on the charge accumulated in each element of the CCD array. The camera control unit, mentioned above, converts the sequence of analog waveforms to frames of video, which may comply with the NTSC, PAL or S video standard for example.
The flexible video endoscope 900 may also include an illumination channel 930 terminating at window 932 and a working channel(s) 940 terminating at distal opening(s) 942.
Though not discussed in detail here, some endoscopes may have rigid, straight, insertion tubes in which an image focused at the distal end is conveyed, via a lens system, to the proximal end. Such endoscopes may also employ illumination channels and working channels.
As alluded to above, many endoscopes include working channels. Depending upon the application of the particular endoscope, various tools may be passed through the working channel. These tools will extend out from the distal end of the insertion tube and may be manipulated by a user at the proximal end on the endoscope. For example, knives, curettes, forceps, scissors, and cauterizing electrodes may be passed through the working channel. Moreover, pressurized gas may be passed via a working channel to insufflate a body cavity, fluid may be passed via a working channel to irrigate a body cavity, and a negative pressure may be introduced to the working channel to suck out irrigation fluid, tissue, or body fluids.
Endoscopes are relatively expensive and thus are typically reused many times. Naturally, between uses, the endoscopes must be cleaned and disinfected or sterilized. For example, when reprocessing the endoscope for use on a next patient, the working channels must be cleaned and disinfected or sterilized. Since, in general, the working channels cannot be visually inspected, there is no direct way of ensuring that they have been adequately cleaned and sterilized. Thus, rigid and time consuming protocols for cleaning the working channels are often implemented. Such a cleaning protocol is discussed below with reference to FIG. 10.
FIG. 10 is a side view of a channel brush 1000 for cleaning the working channel of an endoscope. The channel brush 1000 includes a ring 1010 to be grasped or manipulated with a user's finger(s). A proximal end of a flexible shaft 1020 is attached to the ring 1010. The length of the flexible shaft must be at least as long as the working channel in the insertion tube of the endoscope. A distal end of the flexible shaft 1020 may be provided with a relatively rigid section 1022, a relatively flexible section 1024, and another relatively rigid section 1026. A brush section 1030, typically nylon fibers held in twisted metal wires, is attached to (e.g., by means of soldering, welding, etc.) the second relatively rigid section 1026. A rounded end 1040 is provided to protect the walls of the working channel from the wire ends of the brush section 1030. Another brush for cleaning endoscopes is discussed in U.S. Pat. No. 5,297,310 (incorporated herein by reference). In a typical cleaning protocol, the brush is passed through the detergent-filled working channel of the endoscope three (3) times, during which it is articulated back and forth with shorter strokes. Then the working channel is rinsed and subsequently either flushed with disinfectants or sterilized in an attempt to reprocess the working channel.
The above described reprocessing protocol has a number of disadvantages. First, the manual operation is time consuming. Consequently, the endoscope, a relatively expensive medical resource, is unavailable for use on another patient during reprocessing (also referred to as "endoscope downtime"). Similarly, the person performing the reprocessing is also unavailable to perform other tasks. Second, human training and care may greatly affect the efficacy of the reprocessing protocol.
A number of inventions have been presented in an effort to improve the reprocessing of medical endoscopes. For example, Japanese Patent No. 4-312437, and corresponding U.S. Pat. No. 5,251,356 (incorporated herein by reference) (hereafter referred to as "the Oaki patents"), disclose a motorized brush for cleaning the working channel of an endoscope in which the brush may be rotated and reciprocated. While it is believed that the Oaki patents provide an excellent tool for cleaning the working channels of endoscopes, sterilizing or disinfecting the endoscope is not directly addressed. Japanese Patent No. 4-312441 discloses a motorized brush and insertion tube guide assembly for cleaning the working channels of endoscopes. This patent also discloses a brush used in conjunction with a loop insertion tube guide and a reservoir for cleaning working channels of endoscopes.
U.S. Pat. No. 5,240,675 (hereafter referred to as "the Wilk patent" and incorporated herein by reference) discusses a tool for cleaning and sterilizing the working channels of endoscopes. The tool discussed in the Wilk patent uses radiation and/or heat to sterilize the working channel. A brush and sterilizing fluid may also be used to clean and sterilize the working channel. The brush may be vibrated by means of ultrasonic waves. Unfortunately, it is believed that the vibrating motion of the brush induced by the ultrasonic waves does not clean as thoroughly as a rotating brush.
In view of the above limitations of the known tools for reprocessing endoscopes, and cleaning and sterilizing working channels in particular, an improved tool is needed. Such a tool should thoroughly clean the working channel(s) of an endoscope. It should provide good abrasion of debris from channel surfaces. Finally, it should be simple and relatively quick to use, and it should be relatively portable.